This invention relates to circuit breakers, and, more particularly to a circuit breaker interface mechanism for a bell alarm switch.
It is generally well known in the art of circuit breakers to provide a reset mechanism to reset a tripping device such as an accessory shunt trip or under voltage device. During quiescent operation, (i.e. when the circuit breaker contacts are closed to allow the flow of electrical current) the operating handle of an operating mechanism is in the xe2x80x9cONxe2x80x9d position. To stop the current flow manually, the handle may be shifted to the xe2x80x9cOFFxe2x80x9d position thereby opening the electrical contacts. Upon attainment of a pre-determined condition (trip event), such as ground fault or overload, the operating mechanism of the circuit breaker will release the forces of the mechanism operating springs and release the operating handle to a tripped position between the xe2x80x9cONxe2x80x9d position and the xe2x80x9cOFFxe2x80x9d position. Before the circuit breaker may be turned xe2x80x9cONxe2x80x9d, the operating mechanism must be manually reset. This is accomplished by rotating the operating handle beyond the xe2x80x9cOFFxe2x80x9d position against the bias of the operating mechanism springs, thereby locking the operating mechanism in position.
The same mechanical forces used to direct the operating mechanism from the tripped position to the reset position are used to reset any attached accessories, such as a shunt trip actuator, auxiliary switch accessory, bell alarm or other type of accessory unit. However, as accessories are generally separate components mounted proximate to the operating mechanism, positional variations at the interface of the accessory and the circuit breaker operating mechanism are possible due to manufacturing tolerances. These positional variations can affect the resetting motion translated to the bell alarm switch or its components by not compensating for any over-travel resulting from the possible tolerance variations. Furthermore, a reliable interface mechanism between the circuit breaker and internal accessories is desired that will provide reliable actuation of the bell alarm switch when the breaker changes state in either an overload xe2x80x9ctripxe2x80x9d condition or when a push-to-trip button is depressed without robbing energy from the operating mechanism during such tripping operation, which is common with conventional accessory interface systems. Conventional accessory interface systems between the operating mechanism and accessories presently rely only on limited xe2x80x9ctake upxe2x80x9d provided by the accessory switch. It is further desired that the switch also be field installable by the customer without violating UL requirements.
The above discussed and other drawbacks and deficiencies of the prior art are overcome or alleviated by an assembly for interacting with a circuit breaker operating mechanism of a circuit breaker including a housing and a pair of contacts within the housing, the operating mechanism arranged to separate the pair of contacts upon the occurrence of a trip event. The assembly includes a plurality of linkages arranged to transmit mechanical energy from the operating mechanism to a plunger of an accessory device for changing a state thereof. The system of linkages is configured to compensate for any over-travel resulting from possible tolerance variations.
In an exemplary embodiment of the invention, an assembly for interacting with a circuit breaker operating mechanism of a circuit breaker, the assembly includes an accessory device disposed in the housing including a plunger configured for movement between a retracted position and a protruded position. A cradle pivot pin having operable communication with the operating mechanism is further in mechanical cooperation with a first link that in turn is in mechanical cooperation with a second link. The first link and cradle pivot pin are complimentary configured such that the first link receives the cradle pivot pin therein and rotation relative to each other is prevented. The second link is in further mechanical cooperation with the plunger. When the operating mechanism applies a force to the cradle pivot pin, the force changes a state of the accessory device by being transmitted from the operating mechanism to the cradle pivot pin, from the cradle pivot pin to the first link, from the first link to the second link, and from the second link to the plunger for changing a position of the plunger from either the protruded position or the retracted position.